Hybrid Organic–Inorganic Blast Furnace Slag Binders Activated with Alkali Acetates

Hybrid organic-inorganic binders based on blast furnace slag were produced using sodium (NaAc) or potassium (KAc) acetate as the sole activator, and their properties were compared with those of sodium- or potassium hydroxide-activated slag pastes. The acetate-activated binders showed significantly lower cumulative heat release and extended setting time (∼230 h) than the hydroxide-activated binders. The main reaction products forming in all binders were calcium aluminosilicate hydrate-type gels and a hydrotalcite-like phase, independently of the activator type used. Compressive strengths of the acetate-activated pastes (∼40 MPa at 180 days) were lower than those of the hydroxide-activated binders (∼80 MPa at 180 days). However, the acetate-based binders exhibited superior impermeability and reduced wettability at 28 days, likely due to hydrophobic acetate groups. It is hypothesized that acetates dissociate in water, forming calcium acetate and alkali silicates via a reaction with species dissolving from the slag. This study demonstrates alkali acetates are effective activators for creating hybrid slag-based binders with reduced permeability.